This invention relates to a process for detecting the amount of transported and/or remaining tape on a reel or the like, and more particularly, to a process for detecting such for a reversible type tape recorder in which reproduction can be performed in normal and reverse directions.
As a conventional example of a process for detecting the amount of transported or residual tape in a tape recorder, it has been proposed that firstly, the rotational periods of the pair of tape reels are to be detected, respectively, so that the tape amount may be computed through predetermined operational equations from the thus detected rotational period signals.
According to this electronic method, it is possible to detect the tape amount more accurately than with a conventional mechanical tape counter.
However, in a conventional reversible type tape recorder, there has not been provided any means which detects the amount of the transported/residual tape and displays the amount in terms of the actual time remaining on the tape. Therefore, a successive display of the time representative of the tape amount has been needed for the reversible type tape recorder.
Further, as the tape speed fluctuates for a predetermined period of time just after one operation mode of the tape recorder is changed to the other, it is impossible to compute the tape amount through operational equations, accurately. Therefore, it is unnecessary to detect such a tape amount until the tape speed is stabilized. In such a period, since the tape speed is unstable, the thus obtained rotational period data signal is meaningless.